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Abstract

ABSTRACTChayul–Subansiri River is the largest tributary of the Brahmaputra River basin originated in the Tibet Autonomous Region of China. After flowing about 210.5 km as Chayul in Tibet, it flows as Subansiri in Arunachal Pradesh state of India for 551.5 km before merging into the Brahmaputra River in Assam (India). This study was carried out to understand the hydro-morphometry of the Chayul–Subansiri River as it governs the hydrology and hydro-hazards of the basin. Various linear, areal, and relief parameters were extracted from Suttle Radar Topographic Mission (SRTM) Digital Elevation Model of 30 m spatial resolution using Google Earth Engine and GIS software. On comparison, significant difference has been noticed in various morphometric parameters such as relative relief, dissection index, ruggedness index etc. among the Chayul, Upper Subansiri and Lowe Subansiri sub-basins. Notable difference is also observed between the Upper Subansiri and Lowe Subansiri sub-basins in terms of some key morphometric parameters such as drainage density, stream frequency, constant of channel maintenance, infiltration number, drainage ratio, drainage texture, form factor ratio, elongation ratio etc. Hypsometric analysis has highlighted further the difference in geomorphic fabric, terrain maturity and hydrologic characteristics of these different sub-basins. Since hydro-morphometric parameters have direct bearing on the hydrology, outcome of this study will be useful in decision making on water resources management and in finding engineering solutions to hydro-hazards for this basin. Keywords: Morphometric Analysis, Hypsometry, Chayul, Subansiri, Brahmaputra, GIS